pcnet32: fix BNC/AUI port on AM79C970A

Even though the port autoselection is enabled by default on AM79C970A,
BNC/AUI port does not work because the link is always reported to be
down. The link state reported by the chip belongs only to the TP port
but the driver uses it regardless of the port used. The chip can't
detect BNC/AUI link state.

Disable port autoselection and use TP port by default to keep current
behavior (link detection works on TP port, BNC/AUI port does not work).

Implement ethtool autoneg, port and duplex configuration to allow
using the BNC/AUI port.

Report the TP link state only if the TP port is selected. When the
port autoselection is enabled or AUI port is selected, report the link
as always up.

Move pcnet32_suspend() and pcnet32_clr_suspend() functions to avoid
forward declarations.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: David S. Miller <davem@davemloft.net>